A glyph is an outline representation of a letter, number, symbol, character, etc. in a specific visual form. Glyphs may be rendered on a display device or medium by using raster graphics (or bitmaps). A bitmap includes a matrix of dots or pixels that define a shape delineating the glyph. Raster graphics are faster and easier to use in computer code, but non-scalable and require a separate font for each size. Since raster graphics are resolution-dependent, scaling or resizing raster graphics inevitably causes image quality to suffer.
Alternatively, glyphs may be rendered using vector graphics. Vector graphics are based on geometrical primitives (e.g., points, lines, curves, polygons, etc.) that are represented by mathematical expressions. Unlike raster graphics, vector graphics are resolution independent, and can be scaled to the desired size by scaling the underlying geometry without loss in apparent quality. One type of vector-based font is the TrueType font, which is an outline font standard developed by Apple and Microsoft. Using a TrueType font in which the glyphs are vector-based may overcome the disadvantages of raster graphics. However, traditional TrueType fonts are monochrome, and allows the user to specify only one foreground color.